U.S. patent number 10,046,351 [Application Number 14/679,178] was granted by the patent office on 2018-08-14 for material dispense tracking and control.
This patent grant is currently assigned to Graco Minnesota Inc.. The grantee listed for this patent is Graco Minnesota Inc.. Invention is credited to Mark J. Brudevold, Benjamin R. Godding, Daniel P. Ross, Joseph E. Tix.
United States Patent |
10,046,351 |
Brudevold , et al. |
August 14, 2018 |
Material dispense tracking and control
Abstract
A pump system for pumping a fluid includes a motor housing, a
motor, a rod, a positive displacement pump, a position sensor, and
a controller. The motor is located within the motor housing. The
rod is connected to and driven by the motor and the positive
displacement pump for moving a fluid is driven by the rod. The
position sensor produces a rod position signal that is a function
of a position of the rod, and the controller produces a drive
signal for driving the motor as a function of the rod position
signal.
Inventors: |
Brudevold; Mark J. (Fridley,
MN), Godding; Benjamin R. (St. Cloud, MN), Tix; Joseph
E. (Hastings, MN), Ross; Daniel P. (Maplewood, MN) |
Applicant: |
Name |
City |
State |
Country |
Type |
Graco Minnesota Inc. |
Minneapolis |
MN |
US |
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Assignee: |
Graco Minnesota Inc.
(Minneapolis, MN)
|
Family
ID: |
55066786 |
Appl.
No.: |
14/679,178 |
Filed: |
April 6, 2015 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160008834 A1 |
Jan 14, 2016 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62024278 |
Jul 14, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B05B
12/122 (20130101); F04B 17/00 (20130101); B05B
12/085 (20130101); F04B 49/02 (20130101); B05B
7/166 (20130101); F04B 49/06 (20130101); F04B
19/22 (20130101); B05B 15/50 (20180201); B05B
7/1693 (20130101); B05B 12/006 (20130101); F04B
53/10 (20130101); F04B 53/144 (20130101); F04B
49/065 (20130101); F04B 2201/0201 (20130101); B05C
11/1042 (20130101); F04B 2205/09 (20130101); B05B
9/0423 (20130101); B05B 9/0409 (20130101); B05C
11/1044 (20130101); B05C 5/002 (20130101) |
Current International
Class: |
B05B
12/12 (20060101); F04B 49/06 (20060101); F04B
17/00 (20060101); F04B 49/02 (20060101); F04B
19/22 (20060101); F04B 53/10 (20060101); F04B
53/14 (20060101); B05B 12/00 (20180101); B05C
5/00 (20060101); B05C 11/10 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1692991 |
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Nov 2005 |
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CN |
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103537408 |
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Jan 2014 |
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CN |
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103835931 |
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Jun 2014 |
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CN |
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2404679 |
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Jan 2012 |
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EP |
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2708288 |
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Mar 2014 |
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EP |
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2732884 |
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May 2014 |
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EP |
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Other References
Written Opinion and International Search Report, for PCT No.
PCT/US2015/025521, dated Jul. 23, 2015, 27 pages. cited by
applicant .
International Preliminary Report on Patentability, for PCT Patent
Application No. PCT/US2015/025521, dated Jan. 17, 2017, 23 pages.
cited by applicant .
First Chinese Office Action, for Chinese Patent Application No.
201580035594.2, dated Sep. 12, 2017, 21 pages. cited by applicant
.
Extended European Search Report, for European Patent Application
No. 15821652.3, dated Feb. 12, 2018, 11 pages. cited by
applicant.
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Primary Examiner: Leong; Nathan T
Attorney, Agent or Firm: Kinney & Lange, P.A.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION(S)
This application claims priority to U.S. Provisional Application
No. 62/024,278, which is fully incorporated by reference.
Claims
The invention claimed is:
1. A system for pumping, tracking and controlling a fluid, the
system comprising: a pump system for pumping the fluid, the pump
comprising: a motor housing; a motor located within the motor
housing; a rod connected to and driven by the motor; a pump driven
by the rod for moving a fluid; and a position sensor for producing
a rod position signal that is a function of a position of the rod;
a dispenser for controllably dispensing multiple streams of fluid
received from the pump; a work piece sensor for producing a work
piece signal that is a function of detection of a work piece; and a
controller, the controller comprising a calculating circuit and
computer readable storage media and configured to: receive a
programmed dispenser output from a user interface, produce a drive
signal for driving the motor, produce a dispense signal for the
dispenser that is a function of the work piece signal, produce a
calculated work piece count as a function of the work piece signal,
produce a calculated volume usage as a function of the position
signal, produce a calculated flow rate as a function of the
calculated volume usage, produce a calculated fluid weight as a
function of the calculated volume usage, and produce a calculated
fluid compressibility as a function of the calculated volume
usage.
2. The system of claim 1 and further comprising a sleeve connected
to the motor housing, wherein the position sensor is connected to
the sleeve.
3. The system of claim 1, wherein the position sensor is an
ultrasonic sensor.
4. The system of claim 1, wherein the position sensor is a linear
variable differential transformer sensor.
5. The system of claim 4, wherein the rod acts as a core for the
position sensor.
6. The system of claim 1, wherein the position sensor is connected
to the motor housing.
7. The system of claim 1, wherein the position sensor is a reed
sensor.
8. The system of claim 1, wherein the motor is double ended type
air motor.
9. The system of claim 1, wherein the controller is configured to
receive a programmed dispenser output from a user interface.
10. The system of claim 9, wherein the controller is configured to
adjust the drive signal and the dispense signal as a function of
the volume to meet the programmed dispenser output.
11. The system of claim 10, wherein the controller is configured to
adjust the dispenser signal to vary timing or a stitching
percentage of the dispensed fluid.
12. The system of claim 1, wherein the programmed dispenser output
is a programmed flow rate.
13. The system of claim 1, wherein the programmed dispenser output
is a programmed volume per work piece.
14. The system of claim 1, wherein the dispenser comprises a
plurality of sprayers for spraying multiple streams of fluid, and
wherein each sprayer receives a dispense signal from the
controller.
15. The system of claim 14, wherein the controller calculates
sprayer performance of each sprayer as a function of an adjustment
to the dispenser signals.
16. The system of claim 15, wherein the controller produces the
drive signal as a function of the sprayer performance.
17. The system of claim 16, wherein the controller produces the
dispenser signals as a function of the sprayer performance.
18. The system of claim 1, wherein the controller displays a
real-time value of the calculated flow rate on a user
interface.
19. The system of claim 1, wherein the controller produces an
average flow rate as a function the calculated flowrate, and
wherein the controller displays a real-time value of the average
flow rate on a user interface.
20. The system of claim 1, wherein the controller produces an alarm
as a function of the calculated flow rate when the calculated flow
rate has changed by a prescribed amount, is under a prescribed
minimum value, or is above a prescribed maximum value.
21. The system of claim 1, wherein the controller produces a
per-work piece fluid output as a function of the work piece count
and the calculated flow rate.
22. The system of claim 21, wherein the controller displays a
real-time value of the per-work piece fluid output on a user
interface.
23. The system of claim 21, wherein the controller produces an
alarm as a function of per-work piece fluid output when the
per-work piece fluid output has changed by a prescribed amount, is
under a prescribed minimum value, or is above a prescribed maximum
value.
24. The system of claim 1, wherein the controller produces a
long-term fluid output per work piece as a function work piece
count and calculated flow rate.
25. The system of claim 24, wherein the controller produces a trend
over time of long-term fluid output per work piece.
26. The system of claim 25, wherein the controller uploads data of
the trend over time of long-term fluid output per work piece to a
computer readable storage media.
27. The system of claim 24, wherein the controller displays a
real-time value of the long-term fluid output per work piece on a
user interface.
28. The system of claim 24, wherein the controller produces an
alarm as a function of long-term fluid output per work piece when
the long-term fluid output per work piece has changed by a
prescribed amount, is over a prescribed minimum value, or is above
a prescribed maximum value.
29. The system of claim 1, wherein the controller produces an
average calculated flow rate as a function of calculated flow
rate.
30. The system of claim 1, wherein the controller produces a
dispensed fluid output as a function the calculated flow rate and
the dispense signal.
Description
BACKGROUND
Material dispense systems are systems which dispense a volume of
material onto a receiving surface or work piece. Material dispense
systems often include a controllable dispenser and a pressure
source for pressurizing the material to be dispensed. The material
dispensed can be any useful fluid. Commonly dispensed fluids
include paints, dyes, glues, and lubricants. Some dispensed fluids,
such as glues, must be carefully manipulated into a dispensable
form through several processes, such as heating and pumping.
Material dispense systems are often used in automated or manual
assembly processes. For example, material dispense systems are used
to apply paint to automobiles on assembly lines. Also, material
dispense systems are used to apply glue to boxes for packaging on
assembly lines. A glue frequently used in packaging material
dispense systems is hot melt glue. Hot melt glue must be melted and
pressurized before it can be dispensed. Because the melting
temperature of the glue is often several hundred degrees
Fahrenheit, significant heat is applied to the glue through much of
the process. This can lead to burning, or charring, of glue which
can clog dispensers and slow down production of packaging
materials, such as boxes. Additionally, packaging assembly lines
may consume large quantities of glue, making glue a costly raw
material.
SUMMARY
In one embodiment, a pump system for pumping a fluid includes a
motor housing, a motor, a rod, a positive displacement pump, a
position sensor, and a controller. The motor is located within the
motor housing. The rod is connected to and driven by the motor, and
the positive displacement pump for moving a fluid is driven by the
rod. The position sensor produces a rod position signal that is a
function of a position of the rod, and the controller produces a
drive signal for driving the motor as a function of the rod
position signal.
In another embodiment, a system for tracking and controlling a
fluid includes a pump system, a work piece sensor, a dispenser, and
a controller. The pump system is for pumping the fluid and includes
a motor housing, a motor, a rod, and a position sensor. The motor
is located within the motor housing. The rod is connected to and
driven by the motor and the pump is driven by the rod for moving a
fluid. The position sensor produces a rod position signal that is a
function of a position of the rod. The controller produces a drive
signal for driving the motor as a function of the rod position
signal. The work piece sensor produces a work piece signal that is
a function of detection of a work piece. And, the dispenser
controllably dispenses fluid received from the pump, and the
dispenser receives a dispense signal from the controller that is a
function of the work piece signal.
In another embodiment, a system for tracking and controlling a
fluid includes a pump system, a work piece sensor, a dispenser, and
a controller. The pump system is for pumping the fluid, and
includes a motor housing, a motor, a rod, and a position sensor.
The motor is located within the motor housing. The rod is connected
to and driven by the motor and the pump is driven by the rod for
moving a fluid. The position sensor produces a rod position signal
that is a function of a position of the rod. The dispenser
controllably dispenses multiple streams of fluid received from the
pump. The work piece sensor produces a work piece signal that is a
function of detection of a work piece. The controller produces a
drive signal for driving the motor, and produces a dispense signal
for the dispenser that is a function of the work piece signal. The
controller also produces a calculated work piece count as a
function of the work piece signal, and produces a calculated volume
usage as a function of the position signal.
In another embodiment is a method for tracking and controlling a
fluid including producing a drive signal for driving a motor of a
pump using a controller. The motor is driven to pump a fluid based
on the drive signal. A dispense signal is sent from the controller
to a sprayer for dispensing the fluid. A calculated work piece
count is determined as a function of a work piece signal provided
to the controller from the work piece sensor. The position of a rod
connected to the motor and the pump is detected using a position
sensor. A position signal is created as a function of the position
of the rod using the position sensor. The position signal is sent
to the controller and a calculated volume is determined as a
function of the position of the rod using the controller.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a system for dispensing hot melt
adhesive.
FIG. 2 is a schematic view of the system of FIG. 1.
FIG. 3 is a diagram of operations within the control system.
FIG. 4 is a diagram of operations within the control system.
FIG. 5 is a diagram of operations within the control system.
FIG. 6 is a diagram of operations within the control system.
FIG. 7 is a diagram of operations within the control system.
FIG. 8 is a diagram of operations within the control system.
FIG. 9 is a partial cross sectional view of a pump system.
FIG. 10 is a partial cross sectional view of a pump system.
FIG. 11 is a partial cross sectional view of a pump system.
DETAILED DESCRIPTION
FIG. 1 is a schematic view of system 10, which is a system for
dispensing hot melt adhesive, such as glue. System 10 includes cold
section 12, hot section 14, air source 16, air control valve 17,
and controller 18. Cold section 12 includes container 20 and feed
assembly 22, which includes vacuum assembly 24, feed hose 26, and
inlet 28. Hot section 14 includes melt system 30, pump 32,
dispenser 34, and supply hose 38. Dispenser 34 includes manifold
40, sprayer 42, and outlet 44. Also included in system 10 are air
hoses 35A-35E.
Air control valve 17 is connected to air source 16 by air hose 35A.
Air source 16 also connects to dispenser 34 through air hose 35D,
bypassing air control valve 17. Air control valve 17 is connected
to container 20 by hose 35E. In alternative embodiments, air hose
35E can be connected directly to air source 16, bypassing air
control valve 17, or connected to a different air source (not
shown) or a different air control valve (not shown). Air control
valve 17 is also connected to vacuum assembly 24.
In cold section 12, container 20 connects to vacuum assembly 24 at
inlet 28. The outlet of vacuum assembly 24 connects to feed
assembly 22. Feed hose 26, of feed assembly 22, connects vacuum
assembly 24 to hot section 14. Feed hose 26 connects to hot section
14 at the inlet of melt system 30. Within hot section 14, melt
system 30 connects to pump 32. Pump 32 is mechanically coupled to
motor 36, which is an air motor (as discussed below). The outlet of
pump 32 is connected to dispenser 34 by supply hose 38. More
specifically, supply hose 38 connects to dispenser 34 at manifold
40. Manifold 40 connects to sprayer 42. Also connected to sprayer
42 is air hose 35D (which connects to air source 16). The outlet of
sprayer 42 is sprayer outlet 44.
Controller 18 is electrically connected with several components of
system 10, including air control valve 17, melt system 30, pump 32,
and dispenser 34.
Components of cold section 12 can be operated at room temperature,
without being heated. Container 20 can be a hopper for containing a
quantity of solid adhesive pellets for use by system 10. Suitable
adhesives can include, for example, a thermoplastic polymer glue
such as ethylene vinyl acetate (EVA) or metallocene.
In one embodiment, air source 16 is a source for delivering
compressed air to components of system 10 in both cold section 12
and hot section 14. Air source 16 delivers compressed air to air
valve 17, which selectively controls air flow from air source 16
through air hose 35B to vacuum assembly 24 and through air hose 35C
to motor 36 of pump 32. Air control valve 17 also delivers bursts
of air into container 20 for pressurizing and feeding pellets of
adhesive or hot melt into hot system 14.
Compressed air is also transported from air source 16 to air
control valve 17 and is delivered to vacuum assembly 24 to create a
vacuum. The vacuum created induces flow of adhesive pellets into
inlet 28 of vacuum assembly 24 and then through feed hose 26 to hot
section 14. Feed hose 26 is a tube or other passage sized with a
diameter substantially larger than that of the solid adhesive
pellets to allow the solid adhesive pellets to flow freely through
feed hose 26. Feed assembly 22 delivers the solid adhesive pellets
from container 20 to hot section 14.
Solid adhesive pellets are delivered from feed hose 26 to melt
system 30. Melt system 30 can include a container (not shown) and
resistive heating elements (not shown) for melting the solid
adhesive pellets to form liquid hot melt adhesive. Melt system 30
can be sized to have a relatively small adhesive volume, for
example about 0.5 liters, and can be configured to melt solid
adhesive pellets in a relatively short period of time.
Pump 32 can be a linear displacement pump driven by motor 36. Motor
36 can be an air motor driven by compressed air from air source 16
and air control valve 17. An additional valve can further control
the inlet of compressed air into motor 36, as described below. Pump
32 is driven by motor 36 to pump hot melt adhesive from melt system
30, through supply hose 38, to dispenser 34. Hot melt adhesive from
pump 32 is received in manifold 40 and dispensed by sprayer 42
through sprayer outlet 44. Dispenser 34 can selectively discharge
hot melt adhesive by spraying out of sprayer outlet 44 of sprayer
42 onto an object, such as a package, a box, or another object for
receiving hot melt adhesive dispensed by system 10. Sprayer 42 can
be one of multiple modules that are part of dispenser 34, as
discussed below. Some or all of the components in hot section 14,
including melt system 30, pump 32, supply hose 38, and dispenser
34, can be heated to keep the hot melt adhesive in a liquid state
throughout hot section 14 during the dispensing process.
System 10 can be part of an industrial process, for example, for
packaging and sealing cardboard packages and/or cases of packages.
In alternative embodiments, system 10 can be modified as necessary
for a particular industrial process application. For example, in
one embodiment (not shown), pump 32 can be separated from melt
system 30 and instead attached to dispenser 34. Supply hose 38 can
then connect melt system 30 to pump 32.
Controller 18 controls operation of system 10. Controller 18 sends
and receives signals from air valve 17, melt system 30, pump 30,
and dispenser 34, as described below.
FIG. 2 is a schematic view of system 10, which includes cold
section 12, air source 16, air control valve 17, controller 18,
melt system 30, pump 32, dispenser 34, air hoses 35A-35E, air motor
36, and supply hose 38. Dispenser 34 includes manifold 40, sprayers
42a-42n, and outlet 44. Air motor 36 includes housing 46, air
piston 48, upper chamber 49U, lower chamber 49L, rod 50, position
sensor 52, and air control valve 54. System 10 also includes box
sensor 56, user interface 58, and conveyer 60. Also shown in FIG. 2
are box direction F, glue G, sensor signal S, and boxes B1-B3. Glue
G is an adhesive, such as hot melt glue.
The components of system 10 are connected consistently with FIG. 1.
However, FIG. 2 further shows user interface 58 electrically
connected to controller 18, and box sensor 56 electrically
connected to controller 18. FIG. 2 also shows the components of
motor 36 in further detail.
Housing 46 of motor 36 defines upper chamber 49U and lower chamber
49L, separated by air piston 48. Upper chamber 49U and lower
chamber 49U are physical chambers within motor 46 that contain
pressurized air. Upper chamber 49U and lower chamber 49U are
separately connected to air control valve 54 through porting (shown
in later FIGS.) in motor 36. Air piston 48 is coupled to rod 50,
which passes through housing 46. Rod 50 runs through the center of
upper chamber 49U, passes through housing 46 at and connects to
position sensor 52. Rod 50 also runs through the center of lower
chamber 49L and passes through housing 46 and connects to pump
32.
Position sensor 52 is electrically connected to controller 18. Air
valve 54 is also electrically connected to controller 18. Also
electrically connected to controller 18 is user interface 58. Air
valve 54 is also connected to air control valve 17 (shown in FIG.
1). Also, either air valve 54 or air control valve 17 can include a
pressure regulator (not shown).
FIG. 2 further details dispenser 34, which includes sprayers
42a-42n. Each of sprayer 42a-42n are connected to manifold 40.
Sprayers 42a-42n are also connected to pump 32 by supply hose 38.
Sprayers 42a-42n are further connected, electrically, to controller
18, as is box sensor 56. Both box sensor 56 and sprayers 42a-42n
are located near conveyer 60 in close proximity to boxes B1-B3.
Conveyer 60 is a transport system, such as a conveyer system, for
moving boxes B1-B3 in the direction of box direction F, through
system 10.
Sprayers 42a-42n are fluid dispensers for applying glue, or another
adhesive or fluid, to boxes B1-B3. Sprayers 42a-42n can be needle
type valves, or guns, or other types of dispenser valves. Sprayers
42a-42n operate like a control valve that is selectively opened and
closed based on a dispense signal from controller 18. Sprayers
42a-42n be individually actuated through dispense signals from
controller 18 sent to each of sprayers 42a-42n, or can be actuated
in unison through a dispense single signal sent to all of sprayers
42a-42n.
In operation of one embodiment, pump 32 is powered by motor 36 to
pump glue G from melt system 30, through supply hose 38, to
manifold 40, to be distributed to sprayers 42a-42n. Sprayers
42a-42n spray glue G, motivated by air pressure from manifold 40,
to be applied to boxes B1-B3 moving on conveyer 60. This process is
controlled by controller 18 based on inputs received from box
sensor 56 and shaft position sensor 52. Controller 18 controls the
process by controlling air motor 36 through air control valve 54
and sprayers 42a-42n.
More specifically, conveyer 60 moves boxes B1-B3 in the direction
of box direction F. As boxes B1-B3 travel in box direction F they
pass under box sensor 56 and sprayers 42a-42n. Though boxes B1-B3
are shown, the operation of system 10 also applies to a continuous
supply of boxes, as may be common in a boxing operation. Box sensor
56 is a sensor for detecting the presence of a box, such as an
electro-optical position sensor or photoelectric sensor, but may be
other types of sensors. To detect the presence of a box, box sensor
56 emits a sensor signal S towards the location where boxes pass.
For example, when one of boxes B1-B3 cross sensor signal s, box
sensor S will detect its presence through lack of a reflected
signal, or lack of a received signal. When box sensor 56 detects
the presence of one of boxes B1-B3, box sensor 56 sends a box
detection signal to controller 18.
Though box sensor 56 is described as detecting boxes, box sensor 56
may detect the presence of any work piece and create a work piece
signal for sending to controller 18 based on the detection of a
work piece. The box detection signal can also be a work piece
signal in an embodiment where work pieces other than boxes are
used. After receiving the detection signal from box sensor 56,
controller 18 is then aware that one of boxes B1-B3 is under
sprayers 42a-42n. Also, based on the box detection signal,
controller 18 can perform a box count, or work piece count, adding
up all of the boxes detected and reported to controller 18 by box
sensor 56, as described later.
Simultaneously, air motor 36 will power pump 32 to supply glue g to
supply hose 38. Air motor 36 is powered by pressurized air that is
injected into upper chamber 49U and lower chamber 49L within
housing 46, being controlled by air valve 54. For example, as air
is injected into upper chamber 49U, piston 48 will move from upper
chamber 49U towards lower chamber 49L. When piston 48 reaches the
bottom of housing 46, air valve 54 will actuate, forcing
pressurized air into lower chamber 49L, reversing the direction of
piston 48, sending it from lower chamber 49L towards upper chamber
49U. The movement of piston 48 causes movement of rod 50. Rod 50
activates internal components within pump 32 (described in later
FIGS.), which are coupled to pump 32. Because pump 32 is a
dual-action type of pump, pump 32 pumps glue G when shaft 50 moves
in either direction. This process is described in more detail is
later FIGS.
Sensor 52 is a position sensor capable of detecting the position of
rod 50, to which sensor 52 is connected. Sensor 52 can be an
ultrasonic sensor, an LVDT sensor, a reed switch sensor, or another
type of position sensor, as discussed in later FIGS. Pump 32 is a
positive displacement pump, or constant volume pump, which means
that each full stroke of rod 50 and air piston 48 correlates to a
consistent pumped volume of glue G from pump 32. Similarly, partial
strokes can correlate to portions of the volume pumped by a full
stroke. For example, a half stroke of air piston 48 can equal a
half volume of a full stroke pumped by pump 32, depending on the
geometry and operation of pump 32. Regardless, the relationship
between stroke and volume can be known.
When air motor 36 is in operation, position sensor 52 provides a
signal to controller 18 containing positional information regarding
rod 50, which allows controller 50 to determine the relative
position of rod 50 and therefore the position of piston 48 within
air motor 36. Therefore, by detecting the location of rod 50
relative to sensor 52, a pumped volume can be calculated by
controller 18 based on a position signal generated by sensor 52.
This has several benefits, as discussed below.
When glue G is pumped from pump 32 into supply hose 38, glue G is
forced into sprayers 42a-42n. If sprayers 42a-42n are open,
sprayers 42a-42n will spray or squirt a stream of glue G onto a
surface of a passing box B1-B3. Controller 18 can control sprayers
42a-42n to open and close in unison, or can control sprayers
42a-42n to open and close individually. Controller 18 can also
control sprayers 42a-42n to spray a bead of glue G onto boxes B1-B3
in a constant bead or an intermittent bead, or stitch. The length
of each stitch and the spacing of the stitches, also known as
stitch percentage, can also be controlled by controller 18, through
adjustments to sprayers 42a-42n.
Controller 18 has the ability to adjust the flow rate of fluid
output produced by pump 32. Controller 18 can send a drive signal
to the pressure regulator within air control valve 54 to adjust the
pressure of the air sent to the piston of air valve 54. When the
pressure of the air entering air valve 54 is increased, the piston
within air valve 54 moves faster. Conversely, when the pressure of
the air entering air valve 54 is decreased, the piston moves
slower. When the piston moves faster and slower so too does piston
48 and pump 32. By increasing or decreasing the speed of air valve
54 a comparable change in the speed of pump 32 will occur, which
will increase or decrease the flow rate of glue G pumped by pump
32. This adjustment of the pressure provided by air valve 54 is
often controlled by a voltage regulator controlling the pressure
regulator of air valve 54.
As discussed above, position sensor 52 may detect motion of rod 50
allowing for the volume of glue G pumped by pump 32 to be
calculated. This calculation can be performed in controller 18
based on a position signal sent from position sensor 52 to
controller 18, which contains positional information regarding rod
50. Once controller 18 calculates a volume pumped by pump 32,
controller 18 can also perform several additional calculations and
system adjustments, as discussed below.
Controller 18 can send any of its calculations or information
regarding its calculations or operation of system 10 to user
interface 58. User interface 58 can be a local on-site user
interface, or human interface, such as a keypad, or may be a remote
user interface, such as a computer connected wirelessly or by
network cable to controller 18. User interface 58 allows for a user
or program to read and download data from controller 18. User
interface 58 also allows a user or program to input parameters into
controller 18, as described below.
One problem in the prior art is tracking and optimizing glue usage.
Many processes use large volumes of adhesives per day. For example,
a process in a factory may use one pallet of adhesive per day,
which may be 1000-2000 lbs. (455-909 kg) of adhesive. Because the
volumes used are so large and the packaging volumes are also large,
the usage tracked may not be very granular. For example, a process
using one pallet of adhesive per day may only track adhesive or
glue usage in units of pallets per day. This is not an accurate
unit of measurement when a work piece may use, for example, one
ounce (28 g) of glue or adhesive. Therefore, accurate calculations
to determine usage per box or work piece and calculations during
operation often cannot be performed.
The present disclosure solves these issues by providing the ability
to track volumes more accurately. Controller 18 may determine the
volume used per work piece or per unit time based on its
calculation of a measured volume of glue used. The volume of glue
pumped per pump cycle varies depending on the size of the pump. For
example, a pump may produce 5 fluid ounces (148 mL) per full cycle
of pump piston 124. In an embodiment where each stroke is tracked,
controller 18 may determine the volume usage based on increments of
5 fluid ounces (148 mL). However, in embodiments where the position
of rod 50 can be detected, such as in FIG. 1, much smaller volume
usages may be determined. For example, half strokes, or quarter
cycles may be detected, which allow for accuracy of 1.25 fluid
ounces (37 mL). Even finer detection and volume usages may be
determined by controller 18.
By obtaining information on pumped volumes and flowrates, adhesive
usage can be tracked. This allows for process optimization to be
performed on system 10, which saves time and money. For example,
adjustments to volume output can be input into user interface 58 as
described above, which can then be implemented and confirmed by
controller 18. These adjustments can allow for output to be more
consistent, increasing product quality and efficiency.
Also, in the prior art, these adjustments often need to be made
manually and confirmed by observation. The present disclosure saves
significant time and energy through these optimizations.
FIG. 3 is a flow diagram of operations within controller 18. FIG. 3
includes Time 62, piston position 64, pumped volume 66, flowrate
(t) 68, box detection 70, box count 72, and flowrate (b) 74. Time
62, piston position 64, pumped volume 66, flowrate (t) 68, box
detection 70, box count 72, and flowrate (b) 74 are all operations
within controller 18.
Controller 18 receives input from position sensor 52 (of FIG. 2),
as described above, providing controller 18 with piston position 64
of air piston 48 within air motor 36. Piston position 64 can then
be stored in memory within controller 18. Controller 18 can then
compare piston position 64 to stored values of piston position 64
to determine if there has been a change. Any change in piston
position 64 can be correlated to pumped volume 66 by controller 18.
Once pumped volume 66 is obtained, controller 18 can divide pumped
volume 66 by a time increment to determine flowrate (t) 68. Time
intervals such as seconds, minutes, or hours may be used along with
pumped volume 66 in units of fluid ounces, milliliters, or liters
to produce flowrate (t) 68 in units of milliliters per second
[mL/s], where flowrate (t) 68 is a volumetric flowrate. For
example, if 20 milliliters are pumped in 10 seconds, controller 18
may determine that flowrate (t) 68 is 2 [mL/s]. The flow rate may
be calculated as a ratio of the total volume pumped over a day
divided by a total operation time in a day, giving a long-term
flowrate. The flow rate can also be calculated as a ratio of the
volume pumped in any given minute or second, resulting in a
short-term flowrate.
As discussed above, controller 18 receives a box detection signal
from box sensor 56 (shown in FIG. 2). Using this signal, controller
18 determines the presence of a box, producing box detection 70.
Controller 18 can store, in memory within controller 18, every
instance of box detection 70. Controller 18 can then add up these
instances in small or larger quantities to create box count 72. Box
count 72 can be simply a count of 1 box or can be a count of many
boxes, such as 1,000 boxes. After obtaining box count 72, pumped
volume 66 can be divided by box count 72 to produce a volumetric
flowrate on a per box basis, flowrate (b) 74. Flowrate (b) 74 can
be a volume per box or a volume per, for example 1,000 boxes.
In one embodiment, the flow output of each of dispensers 42a-42n
(of FIG. 1) can be determined based on the flowrate (b) 74 and the
dispense signals sent to each of dispensers 42a-42n. This
calculation can also be performed based on flowrate (t) 68.
FIG. 4 is a diagram of operations within controller 18. FIG. 4
includes user interface 58, time 62, pumped volume 66, flowrate (t)
68, box detection 70, box count 72, flowrate (b) 74, box rate 76,
average box rate 78, average algorithm 79, average box detection
80, average box count 82, average pumped volume 84, average
flowrate (t) 86, average flowrate (b) 88, and alarm 90, which are
all operations within controller 18.
Based on box detection 70 and time t, controller 18 can calculate
box rate 76, which is a rate at which boxes, such as boxes B1-B3
(shown in FIG. 2) pass through system 10. Box rate 76, along with
pumped volume 66, flowrate (t) 68, box detection 70, box count 72,
and flowrate (b) 74 can be input into average algorithm 79 along
with time 62. Average algorithm 79 uses memory within controller 18
to store many values of each of each of pumped volume 66, flowrate
(t) 68, box detection 70, box count 72, and flowrate (b) 74, and
box rate 76. Average algorithm 79 then can average these values
based on a number of stored variables, and over a given time. For
example, flowrate (t) 68 can be averaged based on the previous 10
flowrates, or can be averaged based on the number of flowrates in
the previous hour of production. Flowrate (t) 68 can also be
averaged over the period of a production run or of a day.
In another embodiment, flowrate (b) 74 can be averaged on a per box
basis. The volume of fluid per box can be averaged over short and
long time durations, for example the volume of fluid per box can be
averaged per hour or per minute. Also, the volume per box can be
averaged based on short term and long term numbers of boxes. For
example, the volume of glue per box can be averaged over the
previous 10 or 1000 boxes to have glue applied.
Similarly, average algorithm 79 can average any of pumped volume
66, flowrate (t) 68, box detection 70, box count 72, and flowrate
(b) 74, and box rate 76. All of these values can be sent from
controller 18 to user interface 58 to be displayed in real
time.
Also, alarms can be sent to user interface 58. Alarm 90 receives
inputs from pumped volume 66, flowrate (t) 68, box detection 70,
box count 72, flowrate (b) 74, box rate 76, average box rate 78,
average box detection 80, average box count 82, average pumped
volume 84, average flowrate (t) 86, and average flowrate (b) 88.
Alarm 90 then compares these values to stored values for each of
these inputs and to minimum and maximum values for each input,
which can be used to create a prescribed operating range. Alarm 90
can then send an alarm to user interface 58 if any of these inputs
goes out of the prescribed range. For example, an alarm may be sent
from controller 18 to user interface 58 when the flowrate (t) 68
has changed by a prescribed amount, has fallen under a prescribed
minimum flow rate value, or has risen above a prescribed maximum
flow rate value. Similarly an alarm may be sent from controller 18
to user interface 58 when the flowrate (b) 74, dispensed per box,
has changed by a prescribed amount, has fallen under a prescribed
minimum flow rate value, or has risen above a prescribed maximum
flow rate value. When alarm 90 determines that any alarm value has
been reached, alarm 90 can send a signal to user interface 58 for
an alarm to be signaled on user interface 58. The alarm on user
interface 58 can be visual, audible, or otherwise.
Similarly, user interface 58 receives inputs from pumped volume 66,
flowrate (t) 68, box detection 70, box count 72, flowrate (b) 74,
box rate 76, average box rate 78, average box detection 80, average
box count 82, average pumped volume 84, average flowrate (t) 86,
and average flowrate (b) 88. User interface 58 can display any of
these inputs visually, audibly, or in another way.
FIG. 5 is a diagram of operations within controller 18. FIG. 5
includes user interface 58, time 62, pumped volume 66, flowrate (t)
68, box detection 70, box count 72, flowrate (b) 74, box rate 76,
average box rate 78, average box detection 80, average box count
82, average pumped volume 84, average flowrate (t) 86, average
flowrate (b) 88, alarm 90, and trend 92, which are all operations
within controller 18.
Time 62, pumped volume 66, flowrate (t) 68, box detection 70, box
count 72, flowrate (b) 74, box rate 76, average box rate 78,
average box detection 80, average box count 82, average pumped
volume 84, average flowrate (t) 86, and average flowrate (b) 88 can
all be inputs into trend 92. Controller 18 has the ability to store
the results of these inputs in computer readable storage media
within controller 18. For example, controller 18 may store all of
the values of flowrate (b) 74. Then, trend 92 can create a trend as
a function of the stored input data. For example trend 92 can
create a trend of average flowrate (t) 86 versus time 62. Trend 92
can also create a trend of any input as a function of another
input. For example, trend 92 can create a trend of average flowrate
(b) 88 versus box count 72.
Controller 18 can then make these trends available for upload by
controller 18 and available for download at user interface 58 to a
computer readable storage media within user interface 58, or
connected to user interface 58. Trend 92 can also simply send the
trends to user interface 58 for display purposes, such as being
displayed on a human interface. Further, alarm 90 can output an
alarm to user interface 58 if any trends fall outside a
predetermined minimum, maximum, or rate of change.
FIG. 6 is a diagram of operations within controller 18. The
operations include measure variables 94, adjust prayer performance
96, measure variables 98, calculate variable changes 100, determine
sprayer performance 102, and adjust sprayer performance 104.
Controller 18 (shown in FIG. 2) has the ability to send individual
signals to sprayers 42a-42n (shown in FIG. 2), as described above.
Using this capability, controller 18 can determine individual
sprayer performance. In one embodiment, an array of sprayers
includes three sprayers, sprayers 42a, 42b, and 42c, each receiving
an independent control signal. In this embodiment, controller 18
can make variable measurement 94 while all three sprayers are
operating in unison. Variable measurement 94 can be of any inputs
described in the above FIGS., such as time 62, pumped volume 66,
flowrate (t) 68, box detection 70, box count 72, flowrate (b) 74,
box rate 76, average box rate 78, average 79, average box detection
80, average box count 82, average pumped volume 84, average
flowrate (t) 86, average flowrate (b) 88, alarm 90, and trend
92.
Then, controller 18 can perform the step adjust sprayer performance
96 on sprayer 42a. The adjustment can be to not dispense at all for
one box cycle, can be to change the time that sprayer 42a is open,
or any other adjustment affecting the output of glue G from sprayer
42a. Then, controller 18 can perform the step measure variables 98
during this adjustment to sprayer 42a. Most often, controller 18
will measure the same variables in step measure variables 94, and
step measure variables 98.
Next, controller 18 can perform the step calculate variable changes
100 by comparing the variables measured in step measure variables
94 and step measure variables 98. For example, controller 18 can
compare the volume output for a single box from step measure
variables 94 to the volume output for a single box during from step
measure variables 98. Further, other calculations may be performed
based on the data obtained from these two steps. Based on this
comparison, controller 18 can perform the step determine sprayer
performance 102. For example, controller 18 can compare flowrate
(b) 74 determined at step measure variable 94 to flowrate (b) 74
determined at step measure variable 98. Any change in flowrate (b)
74 allows controller 18 to make a determination of how sprayer 42a
is performing. Based on the step determine sprayer performance 102,
controller 18 can perform the step adjust sprayer performance 104.
Continuing the previous example, if controller 18 determines
sprayer 42a is seriously underperforming, controller 18 may infer
that sprayer 42a is clogged and turn sprayer 42a off. Other
adjustments, such as increasing or decreasing flow through sprayer
42a may also be performed.
Further, once performance of one or more sprayers is known,
Controller 18 may adjust the dispense signals to sprayers 42a-42n
or may adjust the drive signal sent to control pump 32, to adjust
output of sprayers 42a-42n. Also, if sprayer performance is
determined to be over or under a predetermined set-point an alarm
may be sent to user interface 58.
One problem that exists in the prior art is charring, or burning of
glue or adhesive that occurs throughout a dispensing system. This
phenomenon is particularly problematic when it results in clogging
of a nozzle of a sprayer or an entire sprayer. This disclosure
addresses this issue by calculating performance of individual
sprayers or dispensers. As discussed above, controller 18 can make
adjustments to a sprayer to determine its performance. If the
sprayer's performance is lower than expected, or lower than the
other sprayers within the dispenser array, controller 18 may
determine that a clog exists in the sprayer. Then, an alarm can be
sent to user interface 58 to notify a user of a clog. Further,
controller 18 can increase the output of the other sprayers in the
array of sprayers to compensate for the clogged sprayer. This
allows for the process to continue to operate effectively and
efficiently until a more convenient or desired time arises to
repair the clogged sprayer, for example at the end of a shift, or
at the end of a production batch, saving time and cost.
FIG. 7 is a diagram of operations within controller 18. The
operations include user input 106, measure variables 108, calculate
adjusted variable 110, and adjust performance 112.
In operation of one embodiment, a user performs the step user input
106 and enters input into user interface 58. Controller 18 then can
perform the step measure variables 108, where controller 18
measures any of the variables described in the FIGS. above, for
example flowrate (b) 74. Based on the data received from the step
user input 106 and measure variables 108, controller 18 can perform
the step calculate adjusted variable 110, where controller 18
adjusts the variable measured based on data received from user
input 106. After adjusting variables, controller 18 can perform the
step adjust performance 112, where controller 18 can adjust the
performance of any component is system 10 based on the new variable
value determined in step calculate adjusted variable 110. This
adjustment allows for more accurate calculations to be performed by
controller 18.
For example, a user may input a density of glue G being pumped by
pump 32. Controller 18 can then calculate the mass or weight of
glue G pumped by multiplying the volume pumped by the known
density, or m=p*V, where m is mass, p is density, and V is
volume.
In another example, the compressibility of the glue or adhesive may
also be entered into controller 18 through user interface 58.
Similarly, other properties of the glue may be entered into user
interface 58 that allows controller 18 to calculate the
compressibility of glue G. Knowing the compressibility of glue G
allows controller 18 to more accurately determine volume pumped by
pump 32 by comparing a measured pressure of glue G downstream of
pump 32, or based on a known relationship of pressure applied to
glue G based on the reciprocating speed of pump 32 and a known
system pressure curve.
Also, a desired dispenser output may be entered into controller 18
through user interface 58. The desired output may be, for example,
a desired flowrate (b) 74 output from sprayers 42a-42n, or a
desired flowrate (t) 68. When controller 18 is given a command to
control to a desired output, controller 18 may then control air
motor 36 (shown in FIG. 2) and sprayers 42a-42n (shown in FIG. 2)
to meet the desired output. For example, glue G can be laid or
sprayed on box 1 in a constant bead or an intermittent bead, also
referred to as a stitch. In an attempt to control to the desired
output, controller 18 can adjust the time sprayers 42a-42n are open
to vary the size of the bead, or the size and quantity of the
stitches applied to a given box. Controller 18 can also turn on and
off some of sprayers 42a-42n, or not open them, to increase or
decrease the output of sprayers 42a-42n to meet the desired
output.
Also, controller 18 can adjust the signal sent to control the speed
of air valve 54, as discussed above, by adjusting the pressure
regulator of valve 30. This increases or decreases the flow rate of
glue G output by pump 32. This adjustment to pressure and flow rate
can be done to meet the desired output of sprayers 42a-42n.
FIG. 8 is a diagram of operations within controller 18. The
operations include produce a drive signal 134, drive a motor 136,
send a dispense signal 138, determine calculated work piece count
140, detect rod position 142, create a position signal 144, and
determine a calculated volume.
As previously discussed, a drive signal can be sent by controller
18 (shown in FIG. 1) to air motor 36 (shown in FIG. 1) to drive
pump 32. In one embodiment, controller 18 can perform the step
produce a drive signal 134, which results in the step drive motor
136, where air motor 36 is driven. Controller 18 can also perform
the step send a dispense signal 138, where a dispense signal is
sent to dispenser 34 (of FIG. 1) or sprayers 42a-42n (of FIG. 2).
Controller 18 can also perform the step determine a calculated work
piece count 140 as a function of the box detection signal provided
by box sensor 56 (shown in FIG. 1). Based on this, controller 18
can perform the steps detect rod position 142 and create a position
signal 144. Following these steps, controller 18 can perform the
step determine a calculated volume 146.
FIG. 9 is a partial cross sectional view of pump 32 and air motor
36 of system 10. FIG. 9 also includes rod sections 50a-50d,
position sensor 52, and sleeve 114. Pump 32 includes rod 50d,
supports 116, inlet 118, outlet 120, seal 122, pump piston 124, and
pump housing 125. Air motor 36 includes, housing 46, air piston 48,
upper chamber 49U, lower chamber 49L, rod sections 50a-50c, air
control valve 54, porting 126, seal 128, and air cylinder 130.
Housing 46 includes housing top 46T, housing bottom 46B, and
housing sidewall 46W. Also shown in FIG. 1 are directions D1 and
D2.
Housing 46, including housing top 46T, housing bottom 46b, and
housing sidewall 46W define air cylinder 130, in which air piston
48 resides. Housing top 46T and housing sidewall 46W of air motor
36 also define upper chamber 49U, and housing bottom 46U and
housing sidewall 46W define lower chamber 49L. Upper chamber 49U
and lower chamber 49L are separated by piston 48. Upper chamber 49U
and lower chamber 49U are physical chambers within motor 46
containing pressurized air, and are separately connected to air
control valve 54 through porting 126.
Air motor 36 is connected, structurally, to pump 32 by supports
116. Rod 50, which is a metal cylinder, couples air motor 36 to
pump 32. Rod 50 passes through both ends of air motor 36. Air
piston 48 is coupled to rod 50b in upper chamber 49U and air piston
48 is coupled to rod 50c in lower chamber 49L. Rod 50b passes
through housing top 46T and becomes rod 50a, which extends into
sleeve 114, which is fastened to motor housing 46. Rod 50c passes
through housing bottom 46B and becomes rod 50c, which connects to
pump piston 124 of pump 32.
Also connected to housing 46 is air valve 54. Air valve 54 is also
connected to air hose 35c (of FIG. 1). Air valve 54 is in fluid
communication with both sides of air piston 48 through porting 126.
Air valve 54 is also in fluid communication with incoming
pressurized air from air control valve 17 through air hose 35c
(both shown in FIG. 1), and the ambient environment or another
relatively low pressure source. Physically, air valve 54 is
attached and secured to housing wall 46W.
Air piston 48 is movable within cylinder 130 and is connected to
rod 50, which passes through air piston 48. Rod 50 may be a single
piece passing through and coupled to air piston 48, or may be
multiple pieces fastened together to make a single functional
piece. Air piston 48 is cylindrical having an outside diameter
approximately equivalent to the inside diameter of housing 46 or
cylinder 130. Air piston 48 includes seal 128 attached to the outer
diameter of air piston 48 that contacts the wall of cylinder 130 or
the inner diameter of housing wall 46W. Air piston 48 is composed
of metal but other materials resistant to failure at operating
conditions, such as plastics, can be used.
Connected to the outside of housing top 46T of air motor 36 is
sleeve 114. Sleeve 114 is predominantly shaped like a hollow
cylinder connecting at one end to air motor 36 and the other end to
position sensor 52. Sleeve 114 may be composed of plastic or metal,
depending on operating conditions. Sleeve 114 is fastened to
housing 46 of motor 24 through a fitting, such as a threaded
fitting, or other fastening means. Rod 50a extends into sleeve 114,
but stops short of position sensor 52 at the end of sleeve 114
distal from air motor 36.
Connected to the outside of housing bottom 46B of air motor 36 is
pump 32. Air motor 36 connects to pump 32 through supports 116 and
rod 50 as described above. Within pump 32, rod 50d passes through
seal 122 and connects to pump piston 124. Rod 50d is coupled or
otherwise fastened to pump piston 124. Pump piston 124 is movable
within pump 32 and is in fluid communication with inlet 118 and
outlet 120.
Pump housing 125 of pump 32 houses the components of pump 32 and
also contains the pressure of fluid within pump 32 around fluid
piston 124. Further, seal 122 of pump 32 surrounds rod 50d, where
rod 50d enters pump housing 125. Seal 122 prevents the escape of
the fluid from pump 32, prevents entrainment of pressurized air
into pump 32, and prevents other foreign substances from entering
pump 32. Similarly, a seal will be used where rod 50d penetrates
housing bottom 46B and housing top 46T to prevent pressurized air
from escaping from air motor 36, or to prevent the fluid or other
foreign substances from entering air motor 36.
Supports 116, which connect pump 32 and air motor 36, are rigid
mounts composed of a material, such as metal, to ensure that pump
32 and air motor 36 remain in alignment. Alignment of pump 32 and
air motor 36 ensures smooth operation and reciprocation of air
piston 48, rod 50, and pump piston 124, which increases efficiency
of pump 32, increases life of the components of pump 32, and the
accuracy of position sensor 52.
In operation of one embodiment, air valve 54 receives pressurized
air from air hose 35c and directs pressurized air to a first side
of air piston 48 through a first path in porting 126, for example
upper chamber 49U. Simultaneously, the second side of air piston
48, for example 49L, will be exposed to a much lower pressure, such
as ambient pressure, through a second path in porting 126. This
causes air piston 48 to move in a direction from the upper chamber
49U to lower chamber 49L, in direction D1. Motion of air piston 48
in direction D1 causes rod 50 to move in direction D1, which also
causes motion of pump piston 124 in direction D1.
Motion of pump piston 124 in direction D1 creates a pumping action,
which motivates a fluid, such as glue, paint, or other fluid, to
travel from inlet 118 to outlet 120 at a desired pressure and
flowrate. When air piston 48 and pump piston 124 reach the end of
their stroke, air valve 54 will change direction. This can be
accomplished through timing, i.e. air valve 54 can be designed to
have a return spring that returns its piston at the same time that
air piston 48 reaches the end of its stroke. Changing the direction
of the piston within air valve 54 can also be accomplished through
controls. An end switch, or multiple end switches, can be used to
produce a signal when air piston 48 has reached the end of its
stroke. This signal is sent to controller 18, which uses the signal
to instruct air valve 54 to reverse its piston.
At this point, air valve 54 will slide or reciprocate to another
position, connecting lower chamber 49L with pressurized air, and
connecting the upper chamber 49U with ambient pressure, or another
low pressure source. This causes air piston 48 to reverse
directions and move in direction D2. This causes rod 50 to move in
direction D2, which drives pump piston 124 in direction D2. Because
pump 32 is a double-action pump, such as a 2-ball or 4-ball double
action pump, motion of pump piston 124 in the direction of D2 will
also motivate fluid to travel from inlet 118 to outlet 120. In
other words, motion of pump piston 124 in either direction D1 or D2
results in the pumping of fluid, or glue G, from inlet 118 to
outlet 120.
When air piston 48 moves in direction D1, so does rod 50a, which
resides in sleeve 114. When rod 50a is fully extended into sleeve
114, rod 50 does not extend fully through sleeve 114, but stops
short of making contact with position sensor 52 leaving a gap
between the end of rod 50 and position sensor 52, which is
positionally fixed.
In one embodiment, position sensor 52 is an ultrasonic detector for
detecting the position of rod 50. Position sensor 52 does this by
sending an ultrasonic pulse down sleeve 114 towards rod 50. When
the pulse reaches rod 50 it will reflect back towards position
sensor 52. Position sensor 52 then detects the reflected pulse and
calculates the distance of rod 50 from position sensor 52 as a
function of the difference between the time the pulse was
transmitted and the time the reflected pulse was received.
Because pump 32 is a constant displacement pump, each full stroke
of rod 50 correlates to a consistent pumped volume from pump 32.
Similarly, partial strokes can correlate to portions of the volume
pumped by a full stroke. For example, a half stroke of air piston
48 can equal half of the volume of a full stroke of air piston 48,
depending on the geometry and operation of pump 32. Regardless, the
relationship between stroke and volume can be known. Therefore, by
detecting the location of rod 50 relative to position sensor 52, a
pumped volume can be calculated. This has several benefits as
discussed above.
FIG. 10 is a partial cross sectional view of another embodiment of
pump 32 and air motor 36a of system 10. Elements of FIG. 10 that
are similar to elements of FIG. 9 are identified by similar
character reference numbers. FIG. 10 also includes position sensor
52a, and sleeve 114a. Pump 32 includes rod 50d, supports 116, inlet
118, outlet 120, seal 122, pump piston 124, and pump housing 125.
Air motor 36a includes, housing 46, air piston 48, upper chamber
49U, lower chamber 49L, rods 50a-50c, air control valve 54, porting
126, seal 128, and air cylinder 130. Housing 46 includes housing
top 46T, housing bottom 46B, and housing sidewall 46W. Also shown
in FIG. 1 are directions D1 and D2.
The components of FIG. 10 are connected similarly to the components
of FIG. 9. However, in air motor 36a, rod 50a, position sensor 52a,
and sleeve 114a form LVDT 132, which is a linear variable
differential transformer (LVDT). In one embodiment, sleeve 114a
contains coils (not pictured) surrounding rod 50a. The coils are
fixed within sleeve 114a and cannot move relative to sleeve 114a or
air motor 36, as sleeve 114a is fastened to housing top 46T.
Rod 50a is a ferromagnetic material, such as steel, and
reciprocates within sleeve 114a, acting as the core of LVDT 123.
Position sensor 52a contains a processor and circuitry required to
determine movement of rod 50a within sleeve 114a, produce a signal
based on the movement of rod 50a, and power the coils within sleeve
114a.
In operation of one embodiment, one or more primary coils within
sleeve 114a produce a voltage, which causes a voltage to be induced
in the secondary coils of sleeve 114a through rod 50a. The voltage
signals induced in the secondary coils change as rod 50a moves
relative to the coils within sleeve 114a, and are detected by the
circuitry and processor of position sensor 52a. This allows the
position of rod 50a to be determined relative to sleeve 114a.
Therefore, the position of rod 50a and air piston 48, which are
connected to rod 50a, can also be determined. The result is the
creation of a position signal by LVDT 123 based on the position of
rod 50a relative to housing sleeve 114a. As discussed in previous
FIGS., by detecting the location of rod 50 relative to sleeve 114a,
a pumped volume and other performance indicators can be
calculated.
FIG. 11 is a partial cross sectional view of pump 32 and air motor
36 of system 10. FIG. 11 also includes position sensor 52b, and
sleeve 114b. Pump 32 includes rod 50d, supports 116, inlet 118,
outlet 120, seal 122, pump piston 124, and pump housing 125. Air
motor 36 includes, housing 46, air piston 48, upper chamber 49U,
lower chamber 49L, rods 50a-50c, air control valve 54, porting 126,
seal 128, and air cylinder 130. Housing 46 includes housing top
46T, housing bottom 46B, and housing sidewall 46W. Also shown in
FIG. 11 are directions D1 and D2. Elements of FIG. 11 that are
similar to elements of FIGS. 9 and 10 are identified by similar
character reference numbers.
The components of FIG. 11 are connected similarly with the
components of FIG. 9. However, in FIG. 11, position sensor 52b is
attached to housing 46 and sleeve 114b is closed on the end away
from air motor 36. Position sensor 52b is securely fastened to
housing wall 46W and partially penetrates housing 46. Position
sensor 52b includes a device for detecting the end of a stroke of
air piston 48, for example a reed switch.
In operation of one embodiment, air piston 48 will reciprocate
within pump housing 46. Position sensor 52b will detect when air
piston 48 reaches the top or end of its stroke and create a binary
or analog signal based on this detection. In effect, position
sensor 52 produces a signal that can be used to count the number of
reciprocations made by air piston 48.
Because motor pump 32 is a positive displacement or constant volume
pump, each reciprocation of air piston 48, which equates to a full
cycle of pump 32, delivers a constant volume of fluid from pump 32.
Therefore, by counting the number of reciprocations made by air
piston 48 and pump piston 124, a pumped volume and flow rate can be
calculated by controller 18.
In this embodiment, sleeve 114b is not required for position sensor
52b to operate effectively. However, sleeve 114b provides
additional benefits. Rod 50c is necessary to connect air motor 36
to pump 32. As a consequence, rod 50c displaces some volume of
lower chamber 49L. In the prior art, where rod an upper rod is not
used, an upper chamber and a lower chamber will have different
volumes during a stroke or cycle.
By adding rod 50b, the volume of upper chamber 49U becomes the same
as lower chamber 49L during a stroke or cycle of air piston 48.
Because rod 50b is added to air motor 36, so must sleeve 114b be
added to allow rod 50b to reciprocate freely with the reciprocation
of air piston 48. The results is that air piston 48 is acted upon
by equivalent volumes of compressed air on either side of air
piston 48, which results in a constant force and speed transmitted
to pump 32 by air motor 36 during either stroke of air piston 48.
This configuration is sometimes referred to as a double ended air
motor. By using this type of air motor for air motor 36, the
volumes pumped by pump 32 can be more accurately calculated, which
saves time and money.
While the invention has been described with reference to an
exemplary embodiment(s), it will be understood by those skilled in
the art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment(s) disclosed, but that the invention will
include all embodiments falling within the scope of the appended
claims.
* * * * *